1. Field of Use
This invention relates generally to motor scrapers and in particular to mechanisms for moving an ejector blade in the bowl of such scrapers.
2. Description of the Prior Art
A motor scraper typically comprises a tractor unit having engine-driven ground engaging wheels and a scraper unit having a supporting frame on which ground engaging wheels and a scraper bowl are mounted. The bowl comprises a bottom wall, laterally spaced apart side walls and a rear wall and is adapted to receive and contain earth which enters the bowl from the front thereof as the scraper unit is drawn across a job site by the tractor unit. Emptying of the bowl is facilitated by a generally vertically disposed dozer type ejector blade which is located at (or sometimes defines) the rear wall of the bowl and is movable forwardly horizontally across the bowl bottom between the side walls by a suitable blade moving mechanism. Some blade moving mechanisms comprise one or more hydraulic rams, each having a relatively movable cylinder and piston rod, and the ram is connected by a suitable linkage between the ejector blade and some sturdy relatively fixed portion of the scraper unit, such as the ground wheel axle. In such prior art mechanisms each ram reaches an excessive overall length when fully extended to effect full forward travel of the ejector blade. Furthermore, the ram or rams extend at uniform speed and with uniform force.